1. Field of the Invention
The present invention relates to a combustion chamber having vortex generators in an inlet zone.
2. Discussion of Background
In burner configurations having a premixing section and a free outlet in the direction of outflow toward the downstream combustion space, there is frequently the problem of how to produce a stable flame front in the simplest manner at extremely low NOx, CO and UHC (=unsaturated hydrocarbons) emissions. Various proposals have already been disclosed in this regard but these are per se unsatisfactory. One exception among those disclosed hitherto is the invention disclosed in EP-A1-0 321 809, the proposals of which concerning the flame stabilization, the efficiency and the pollutant emissions, in particular the NOx emissions, represent an advance in quality. However, there are firing systems in which, for various reasons, the abovementioned subject matter of the invention cannot be used and, as a result, it is necessary in those cases to continue to operate with an obsolete technology, whether diffusion burners are used or whether vortex generators or flame retention baffles are added to the premixing section in the region of the flame front. In the first case, high NOx emissions must always be expected, the discharge quantity of which is no longer compatible with the more recent legal requirements in the countries which provide the most important markets; in the second case a flashback from the flame zone into the interior of the premixing section, especially along the inner wall, where, by the very nature of things, the flow velocity of the combustion air is relatively low, is still possible despite the installation of the proposed measures. A typical firing system in which the said techniques to prevent a flashback will inevitably fail is a combustion chamber designed for self-ignition. This is generally a largely cylindrical tube or an annular combustion chamber into which a working gas at a relatively high temperature flows and mixes there with an injected fuel, the fuel initiating self-ignition. The thermal preparation of the working gas to form hot gas takes place exclusively within this tube or this annular combustion chamber. If this is a secondary combustion chamber which acts between a high-pressure and a low-pressure turbine, space considerations alone make it impossible to fit premixing burners or provide means which would help to prevent a flashback and, for this reason, it has hitherto been necessary to forego this essentially attractive combustion technique. If the postulate extends to providing an annular combustion chamber as a secondary combustion chamber of a gas turbo group mounted on a shaft, additional problems connected with the flame stabilization arise with regard to minimizing the length of this combustion chamber.